This is a little "hack" i used recently to render the default Uploads Content element using Fluid instead of TypoScript

ext_tables.php

<?php

require_once(\TYPO3\CMS\Core\Utility\ExtensionManagementUtility::extPath('famelo') . '/Classes/Content/Uploads.php');

?>

setup.ts

tt_content {
	uploads {
		20 = USER
		20 {
			userFunc = Famelo\Content\Uploads->render
			file = famelo/Resources/Private/Content/Uploads.html
		}
	}
}

Uploads.html

<ul class="list-group">
  <f:for each="{files}" as="file">
		<li class="list-group-item">
			<a href="{file.publicUrl}" >
				<img src="typo3/gfx/fileicons/{file.extension}.gif" />
				{file.name}
			</a>
		</li>
	</f:for>
</ul>

Uploads.php

<?php
namespace Famelo\Sts\Content;

/*                                                                        *
 * This script is backported from the FLOW3 package "TYPO3.Fluid".        *
 *                                                                        *
 * It is free software; you can redistribute it and/or modify it under    *
 * the terms of the GNU Lesser General Public License, either version 3   *
 *  of the License, or (at your option) any later version.                *
 *                                                                        *
 * The TYPO3 project - inspiring people to share!                         *
 *                                                                        */

/*
 */
class Uploads extends \TYPO3\CMS\Frontend\ContentObject\FilesContentObject {

  public $cObj;

	public function __construct() {
		$this->fileFactory = \TYPO3\CMS\Core\Resource\ResourceFactory::getInstance();
	}

	/**
	 * @param string $content
	 * @param array $conf
	 * @return string
	 */
	public function render($content = '', $conf = array()) {
		$this->view = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance('TYPO3\\CMS\\Fluid\\View\\StandaloneView');
		$file = isset($conf['file.']) ? $this->cObj->stdWrap($conf['file'], $conf['file.']) : $conf['file'];
		$templateService = $GLOBALS['TSFE']->tmpl;
		$this->view->setTemplatePathAndFilename($templateService->getFileName($file));
		$this->view->assign('files', $this->getFiles($conf));

		return $this->view->render();
	}

	/**
	 * Rendering the cObject FILES
	 *
	 * @param array $conf Array of TypoScript properties
	 * @return string Output
	 */
	public function getFiles($conf = array()) {
		/** @var \TYPO3\CMS\Core\Resource\FileRepository $fileRepository */
		$fileRepository = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance('TYPO3\\CMS\\Core\\Resource\\FileRepository');
		$fileObjects = array();
		// Getting the files
		if ($conf['references'] || $conf['references.']) {
			/*
			The TypoScript could look like this:# all items related to the page.media field:
			references {
			table = pages
			uid.data = page:uid
			fieldName = media
			}# or: sys_file_references with uid 27:
			references = 27
			 */
			$referencesUid = $this->stdWrapValue('references', $conf);
			$referencesUidArray = \TYPO3\CMS\Core\Utility\GeneralUtility::intExplode(',', $referencesUid, TRUE);
			foreach ($referencesUidArray as $referenceUid) {
				try {
					$this->addToArray($fileRepository->findFileReferenceByUid($referenceUid), $fileObjects);
				} catch (\TYPO3\CMS\Core\Resource\Exception $e) {
					/** @var \TYPO3\CMS\Core\Log\Logger $logger */
					$logger = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance('TYPO3\CMS\Core\Log\LogManager')->getLogger();
					$logger->warning('The file-reference with uid  "' . $referenceUid . '" could not be found and won\'t be included in frontend output');
				}
			}

			// It's important that this always stays "fieldName" and not be renamed to "field" as it would otherwise collide with the stdWrap key of that name
			$referencesFieldName = $this->stdWrapValue('fieldName', $conf['references.']);
			if ($referencesFieldName) {
				$table = $this->cObj->getCurrentTable();
				if ($table === 'pages' && isset($this->cObj->data['_LOCALIZED_UID']) && intval($this->cObj->data['sys_language_uid']) > 0) {
					$table = 'pages_language_overlay';
				}
				$referencesForeignTable = $this->stdWrapValue('table', $conf['references.'], $table);
				$referencesForeignUid = $this->stdWrapValue('uid', $conf['references.'], isset($this->cObj->data['_LOCALIZED_UID']) ? $this->cObj->data['_LOCALIZED_UID'] : $this->cObj->data['uid']);
				$this->addToArray($fileRepository->findByRelation($referencesForeignTable, $referencesFieldName, $referencesForeignUid), $fileObjects);
			}
		}
		if ($conf['files'] || $conf['files.']) {
			/*
			The TypoScript could look like this:
			# with sys_file UIDs:
			files = 12,14,15# using stdWrap:
			files.field = some_field
			 */
			$fileUids = \TYPO3\CMS\Core\Utility\GeneralUtility::trimExplode(',', $this->stdWrapValue('files', $conf), TRUE);
			foreach ($fileUids as $fileUid) {
				try {
					$this->addToArray($fileRepository->findByUid($fileUid), $fileObjects);
				} catch (\TYPO3\CMS\Core\Resource\Exception $e) {
					/** @var \TYPO3\CMS\Core\Log\Logger $logger */
					$logger = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance('TYPO3\CMS\Core\Log\LogManager')->getLogger();
					$logger->warning('The file with uid  "' . $fileUid . '" could not be found and won\'t be included in frontend output');
				}
			}
		}
		if ($conf['collections'] || $conf['collections.']) {
			$collectionUids = \TYPO3\CMS\Core\Utility\GeneralUtility::trimExplode(',', $this->stdWrapValue('collections', $conf), TRUE);
			/** @var \TYPO3\CMS\Core\Resource\FileCollectionRepository $collectionRepository */
			$collectionRepository = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance('TYPO3\\CMS\\Core\\Resource\\FileCollectionRepository');
			foreach ($collectionUids as $collectionUid) {
				try {
					$fileCollection = $collectionRepository->findByUid($collectionUid);
					if ($fileCollection instanceof \TYPO3\CMS\Core\Resource\Collection\AbstractFileCollection) {
						$fileCollection->loadContents();
						$this->addToArray($fileCollection->getItems(), $fileObjects);
					}
				} catch (\TYPO3\CMS\Core\Resource\Exception $e) {
					/** @var \TYPO3\CMS\Core\Log\Logger $logger */
					$logger = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance('TYPO3\CMS\Core\Log\LogManager')->getLogger();
					$logger->warning('The file-collection with uid  "' . $collectionUid . '" could not be found or contents could not be loaded and won\'t be included in frontend output');
				}
			}
		}
		if ($conf['folders'] || $conf['folders.']) {
			$folderIdentifiers = \TYPO3\CMS\Core\Utility\GeneralUtility::trimExplode(',', $this->stdWrapValue('folders', $conf));
			/** @var \TYPO3\CMS\Core\Resource\ResourceFactory $fileFactory */
			$fileFactory = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance('TYPO3\\CMS\\Core\\Resource\\ResourceFactory');
			foreach ($folderIdentifiers as $folderIdentifier) {
				if ($folderIdentifier) {
					try {
						$folder = $fileFactory->getFolderObjectFromCombinedIdentifier($folderIdentifier);
						if ($folder instanceof \typo3\CMS\Core\Resource\Folder) {
							$this->addToArray($folder->getFiles(), $fileObjects);
						}
					} catch (\TYPO3\CMS\Core\Resource\Exception $e) {
						/** @var \TYPO3\CMS\Core\Log\Logger $logger */
						$logger = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance('TYPO3\CMS\Core\Log\LogManager')->getLogger();
						$logger->warning('The folder with identifier  "' . $folderIdentifier . '" could not be found and won\'t be included in frontend output');
					}
				}
			}
		}
		// Rendering the files
		$content = '';
		// optionSplit applied to conf to allow differnt settings per file
		$splitConf = $GLOBALS['TSFE']->tmpl->splitConfArray($conf, count($fileObjects));
		// Enable sorting for multiple fileObjects
		$sortingProperty = '';
		if ($conf['sorting'] || $conf['sorting.']) {
			$sortingProperty = $this->stdWrapValue('sorting', $conf);
		}
		if ($sortingProperty !== '' && count($fileObjects) > 1) {
			usort($fileObjects, function(\TYPO3\CMS\Core\Resource\FileInterface $a, \TYPO3\CMS\Core\Resource\FileInterface $b) use($sortingProperty) {
				if ($a->hasProperty($sortingProperty) && $b->hasProperty($sortingProperty)) {
					return strnatcasecmp($a->getProperty($sortingProperty), $b->getProperty($sortingProperty));
				} else {
					return 0;
				}
			});
		}
		return $fileObjects;
	}
}


?>